Always the gambler, Oakland's general manager worked the phones with Boston counterpart Ben Cherington past 3 a.m. Thursday before coming away with ace Jon Lester in his second blockbuster of the month -- a fearless move that forced Beane to part with his Cuban slugger, Yoenis Cespedes.

In a fascinating trade that sprouted nearly a week ago and further cements the A's belief that they can win a championship this year, they also brought back fan favorite Jonny Gomes and gave the Red Sox their second pick in Competitive Balance Round B in next year's First-Year Player Draft.

Boston is chipping in cash to offset some of the remaining $13 million due Lester, a free agent at season's end.

"Yoenis is a tremendous talent," said Beane. "We've had a tremendous amount of success since he's been here, so it is difficult, but if you're going to separate yourself and try to get a player like Lester, you have to do something that's unique. That's what really captured Boston's attention, the ability to get a player like Cespedes that they can bring back next year."

Lester is very much a two- or three-month rental, depending on how far he can help take the A's, and he'll undoubtedly be too expensive for Beane's checkbook come the offseason. For now, he gives the team a lethal rotation -- as if it wasn't already, with Scott Kazmir, Sonny Gray and Jeff Samardzija already on board. Together, they have a 2.62 ERA.

Either Jason Hammel or Jesse Chavez, both of whom have struggled of late following spectacular starts to the season, will round out the starting staff, to be announced Friday. That's also when Lester and Gomes, as well as outfielder Sam Fuld, brought back to Oakland in a trade that sent lefty Tommy Milone to the Twins on Thursday, are expected at the Coliseum.

"It's a zero-sum game," said Beane. "The less runs you give up, the less you have to score. In Jon Lester's case, we're dealing with a guy who is one of the best at his position in the game and has been a long time. It was just too good of an opportunity to pass up on.

A three-time All-Star who will be a free agent at season's end, the 30-year-old Lester leaves the Red Sox in fine form, having gone 10-7 with a 2.52 ERA in 21 starts this season. His 149 strikeouts are sixth in the American League, and he is fifth in ERA.

The southpaw, who will make his A's debut on Saturday against the Royals at the Coliseum, has also mastered postseason play, posting a 2.11 ERA with six wins, including two in last year's World Series, in 13 playoff appearances spanning 76 2/3 innings.

It's on that same stage the A's have faltered under Beane, who in 16 seasons as the general manager has watched his club make the playoffs seven times but advance past the first round just once, in 2006. Each of the past two seasons, they've been eliminated in decisive Game 5s of the American League Division Series by the Tigers, who one-upped the A's on Thursday by reeling in David Price in the final hour.

Lester is equally imposing, Beane believes, and gives the A's a better chance of overcoming this frustrating postseason history, even though the focus remains on a third straight division title.

"A very good baseball team's right behind us," said Beane, referring to the Angels. "There's no looking ahead. The way the playoff situation is now, you want to win the division, and you want to avoid the one-game playoff situation. We still haven't locked that up."

It's why he's giving up the final year and a half of Cespedes for a short marriage with Lester, and it's why he gave up top prospect Addison Russell and another first-round Draft pick, Billy McKinney, to get Samardzija and Hammel from the Cubs in a trade on July 5.

Oakland was 63-35 with Cespedes in the starting lineup this year and 228-131 with him in the lineup in his two-plus seasons in Oakland. He struggled to maintain consistency, but his raw power has remained a threat throughout. When healthy, he was the A's biggest offensive force and also provided a sensational arm in left field.

The two-time defending Home Run Derby champ hit 23-plus homers in each of his first two seasons after defecting from Cuba. He already has 17 this year and was hitting .256 with a .767 OPS. Now his at-bats will be split between Gomes and Stephen Vogt.

Gomes is hitting .302/.400/.431 vs. lefties, while Vogt is destroying righties at a .365/.396/.524 clip. They've combined for 11 home runs.

"It's not going to be an exact replication, because Yoenis does some things that are pretty special," said Beane, "but hopefully with Lester's addition, you have to score less runs, anyway."

Gomes, 33, had a big impact on the 2013 World Series champion Red Sox and perhaps an even bigger one on the 2012 A's, for whom he lent an impact bat and equally effective leadership skills.

"Yoenis was obviously a very good player on the field and a very popular guy and part of the fabric of this clubhouse the last couple years, so having a guy like Jonny who was also a part of this team two years ago is huge," said Beane. "He brings great qualities, is very popular, knows his role. That was a critical part of this deal for us.

"We're certainly going to miss Yoenis, but we've been in this division for years, say facing a guy like Felix Hernandez. When you can acquire a guy who's at or near that same level, that's the kind of guy you do everything you can to get it done. It was all about Jon Lester and his availability to us."

Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.